Jean-Paul Kneib
title: Cluster Lenses - Nature's Telescope
abstract:
Cluster of galaxies are now well known to display strong gravitational
lensing effects: giant arcs, multiple images and arclets. The lensing
distortion/magnification is a function of the detailled mass distribution,
of the cluster, the distance of the background objects and to a lesser
extend on the cosmological paramters through the angular diameter distance
relations. I will first present what is the current understanding of the
mass distribution in cluster cores. From the mass distribution, we can then
compute the distortion and magnification of these natural lenses, which
properties are used to probe the distant Universe thanks to the
gravitational magnification. In particular I will present new observations
of cluster cores in MIR and Submm, which shade new light in the properties
of distant galaxies.